airdale
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airdale
On a recent road trip I discovered that running GPS mapper Copilot Live (http://copilotlive.com/us/) at full screen brightness with the Nexus 7 plugged into a charger rated at 2.1 amps resulted in a slow battery discharge (3-5%/hour). This was the case with either of two chargers I was carrying. (Yes, both had the proper wiring to make the N7 think it was plugged in to an AC charger.)
Long story short: After 17 total multi-hour tests of five DC chargers and about the same number of cords, I found only one, the Anker 15w (http://www.amazon.com/Anker®-Output-Simul-Port-Charger-Built/dp/B0080AWCTY/ref=cm_cr_pr_product_top), that works. The Anker not only runs the N7 but it simultaneously produces a full-rate battery charge at around 23-25% per hour.
I think the culprit is the USB cords. They seem to have enough resistance that at rated current the voltage at the end of the cord is too low for anything beyond barely sustaining the running N7. Some I tested were better than others but none were good. This is true of the Anker product, too, when tested with a good USB cord rather than its permanently-mounted cord it could run the N7 but only produced a 3%/hour charge rate.
Among the products tested were the pretty and expensive QMadix "Twin Tablet" charger and the compact USAMS "High Output Dual" -- both for sale on Amazon.
Many more gory details available if anyone is interested.
(BTW for highway navigation I like Copilot Live because it does not need a data connection. All its maps are downloaded and resident on your device. I subscribe to data month-to-month and only buy when I am traveling.)
Long story short: After 17 total multi-hour tests of five DC chargers and about the same number of cords, I found only one, the Anker 15w (http://www.amazon.com/Anker®-Output-Simul-Port-Charger-Built/dp/B0080AWCTY/ref=cm_cr_pr_product_top), that works. The Anker not only runs the N7 but it simultaneously produces a full-rate battery charge at around 23-25% per hour.
I think the culprit is the USB cords. They seem to have enough resistance that at rated current the voltage at the end of the cord is too low for anything beyond barely sustaining the running N7. Some I tested were better than others but none were good. This is true of the Anker product, too, when tested with a good USB cord rather than its permanently-mounted cord it could run the N7 but only produced a 3%/hour charge rate.
Among the products tested were the pretty and expensive QMadix "Twin Tablet" charger and the compact USAMS "High Output Dual" -- both for sale on Amazon.
Many more gory details available if anyone is interested.
(BTW for highway navigation I like Copilot Live because it does not need a data connection. All its maps are downloaded and resident on your device. I subscribe to data month-to-month and only buy when I am traveling.)
